Compass



E. F. CLARK.

COMPASS. APPLICATION FILED APR.5, I919- Patented Nov. 23, 1920.

EDWARD rosrnn CLARK, or New: ATTLEBORO,MASSACHUSETTS.

coivrrass.

Specification of Letters Patent. Patflted N QV. 23, 1920.

Application filed April 5, 1919. Serial No. 287,763.

z 0 all, whom it may concern i 1 Be it known that I, EDWARD Fosrnn CLARK, a-citizen of the United States, residmg at North Attleboro, in the county of Bristol and State of Massachusetts, have invented certain new and useful Improve ments in Compasses, of which the following is a specification.

My invention is an improved magnetic compass in which the various necessary parts are so devised as to be capable of being Fig. 2 is a plan view, partly in section of a portion of the outer case, showing the slot therein;

Fig. 3 is a perspective View of part of the inner case, showing the cam slide in position in full and dotted lines;

Fig. 4 is a detail of the cam slide showing its relation to the brake member;

Fig. 5 is a cross sectional elevation on' line 5-5 of Fig. 1;

Fig. 6 is a detail in slide; i

Fig. '7' is a back view of the compass shown in Fig. 1; and

Fig. 8 is a detail of the pivot stud.

The frame work of my improved compass is made up of two cases, an inner and an outer case which, when assembled fit the one within the other and are frictionally engaged. The inner case is regular in shape, a flat bottom 11 is surrounded by a circular wall 12. The bottom is pierced at the center, as at 13 for the upstanding pivot stud 3 which is mounted upon a base 31. The bottom of the inner case is slotted at 14 and the wall is pierced by an aperture 15.

The outer case is made up of a bottom 21 and a circular wall 22. The bottom of the outer case is provided with a central depression 23 and a circumferential depression 24 and also. with a slot 25 through the lower edge of the wall 22.

plan of the cam The cam slide 4 1s provided with spring feet 41 and a lug 42. The brake member, 5

is made up of a ringed head 51 and a point p 52, while the needle 6 is of ordinary construction, having a pivot point 61 midway its length.

wThe parts are assembled by inserting the cam slide 4 through the slot 14, passing the pivot stud 3 through the aperture 13 and inserting the inner case into the outer case, the lug 42 of cam slide 4 being passed through slot 25 in the outer case. The feet 41 of cam slide 4 will now lie beneath the inner case and within the circumferential depression 24 andthe base 31 of pivot 3 will lie within the central depression 23 of the outer case. The cam slide 4, 41, is shaped on a slightly larger circle than the walls of the outer case, so that in assembling the inner case forces the feet to conform to the circle of the outer case, thus drawing the slide 4 into close frictional contact with the wall 12 of the innercase. The cam slide is obviously limited in its motion by the length of the slot 25 through which the lug 42 projects for manipulation from the outside and in setting the inner case the slide is forced backward (to the left in Fig. 3) to the limit and the inner case placed so that the aperture 15 will be exposed beneath the cam surface of the slide 4 (see Figs. 3 and 4).

The brake member 5 is now placed, the ring-head 51 being placed about the pivot 3 and the point 52 being placed within the aperture 15. The needle is now hung upon the pivot 3 and thecrystal 7 sprung into place. It will now be obvious that all the five parts of which the operative parts of the compass are made up are interlocked and held. in their appropriate places by the frictional engagement of the inner and outer cases, the recesses in the bottom of the outer case receiving the base of the pivot and the feet of the cam slide, while the brake member is retained by the pivot and the aperture in the wall of the inner case with which its ends engage. Then the lug 42 is shifted to retract the slide, the needle will be free to swing; when the lug is moved to the other extremity of its range of movement the cam surface of the slide 4 will engage the end 52 of the brake member and will depress it, the brake member pivoting upon the bend 53 as a fulcrum and throwing up the ringhead 51 to engage the underside of the needle pivot 61 and force it against the crystal 7, to be there held while not in use.

I claim: In a compass, a double casing made up of an inner casing having an open edge and an outer casing, the inner casing telescoped within the outer casing and substantially filling the same; a pivot stud made up of a base and an upstanding stud, the base held between the bottoms of the tWo cases and the stud projecting through a central perforation in the bottom of the inner case; a cam slide, 'havinga base held between the bottoms'of the two cases and azlugprojecting to the exterior through a slot in the outer case; a brake :member held by and hetweenzthe pivot stud'and'the Wall of the inner case; a needle pivoted upon the pivot stud; a crystal supported upon the open edge of the inner case and retained by the 15 open edge of the outer case; all combined and operating, substantially as described, to hold in operative position all the parts, by the telescopic engagement of the inner and outer cases.

Signed at North Attleboro, Massachusetts, this 31st day of March, 1919.

EDWARD FOSTER CLAR K. 

